This document provides guidance on design, procurement, and precommissioning activities that will result in the construction of a plant with steam/water-wetted surfaces that are as clean and corrosion-free as practical.

Air blows do not thermally cycle the steam circuit piping and, therefore, are not a recommended substitute for steam blows.

In a steam power plant a steam condenser is used to condense the exhaust steam from the low-pressure turbine. When the steam condenser uses water as the cooling medium and is designed like a shell-and-tube heat exchanger, it is called a surface condenser. When the steam condenser uses air as the cooling medium and is designed like a radiator, it is called an air-cooled condenser (ACC).

The cooling systems at steam-electric power plants represent an important element of the total plant cost of electricity due to capital costs, operating costs, and environmental compliance. The choice of cooling system has a significant effect on plant economics because of the effect on plant efficiency and capacity, and this choice can be affected by climate and hydrology. For example, in some cases a cooling tower can operate more efficiently than a once-through system if water intake temperatures are high, and in other cases the opposite can be true.

Thermal power plants using a water steam cycle require water for many purposes: preparation (commissioning); operation, during which makeup water is needed to compensate for the cycle losses; and potentially also cooling, in case of open circuit (river water direct cooling) or wet-cooling towers (either natural or forced draft).

Mechanical engineers have long worked to produce and distribute energy. The steam engines of Thomas Newcomen (1712) and James Watt (1769), covered in Origins , marked the beginnings of a growing role for mechanical engineers in energy production and distribution. By around 1820 steam had surpassed water as the leading source of mechanical power in Great Britain. The Kew Bridge Cornish steam engine collection illustrates the steady improvements nineteenth-century British engineers made in the design and operation of a key class of steam engines: pumping engines.

Into the early 1800s, the transport of people and goods depended on animal power for overland routes and sailing vessels at sea. When Newcomen designed his atmospheric steam engine in 1712, he likely did not realize the ramifications his invention would ultimately have on transportation. The large, awkward, and heavy pumping engine generated only a few horsepower and could not conceivably move under its own power. Yet the promise of steam power for moving people and goods lay latent in Newcomen's design. Steam power would make important contributions to the expansion and improvement of travel and distribution networks during the First Industrial Revolution.

As a general rule, routine tube sampling is employed to assess the condition and cleanliness of tubes which are filled with steam/water mixtures during service. The primary objectives of routine tube sample collection are to measure the internal deposit weight per unit area and determine the deposit composition. This information is used to determine if a cleaning is required and can be used to assess the performance of the feedwater and boiler water treatment programs.

Industrial steam tables exist to provide a standard set of properties of water and steam for manufacturers, customers, and other parties. Three desirable qualities for a set of industrial steam tables are accuracy, self-consistency, and stability. The properties must be reasonably accurate and self-consistent to support quality design of equipment. A formulation must remain the standard for many years, because the change from one standard to another is inconvenient and expensive. If the tables are represented by computer programs, those programs must be fast, since design software may call steam property routines millions of times. The ASME International Steam Tables for Industrial Use provide highly accurate and self-consistent steam properties, conforming to the constraint of representation by a fast computer program. They are based on the “Revised Release on the IAPWS Formulation 1997 for the Thermodynamic Properties of Water and Steam for Industrial Use,” adopted as an international standard by the International Association for the Properties of Water and Steam. They are suitable for calculations for current and anticipated power plants and are expected to remain the standard for at least 20 years.

Industry uses water throughout the energy supply chains. The purpose and scope of this book is to describe water for the cooling needs of thermoelectric, or steam cycle, power plants. The book focuses on engineering fundamentals along with environmental and economic contexts. Water is an excellent heat transfer medium, and it has historically been abundant and cheap. Thus, thermoelectric , or thermal or steam-electric , power plant cooling needs are usually served by withdrawing and consuming fresh and saline water. Thermal power plants do not have to use water for cooling, but if the desired quantities of water are available, then water-cooling systems are the most economic.

The objective of this chapter is to provide some highlights on the recent issues and lessons learned by the Nuclear Regulatory Commission (NRC) for the safety related and safety significant nuclear power plant components, which utilize the ASME Boiler and Pressure Vessel Codes, Sections III and XI. These include issues related to 2011 Japan Earthquake that directly impacted the Fukushima Nuclear Plant, and also led the regulatory bodies worldwide to take a closer look at the emergency systems for any needed changes for beyond the design basis events. This chapter also provides some information on environmental assisted fatigue of nuclear components exposed to Light Water Reactor (LWR) environments, buried piping leakage and contamination issues, the issues related to High density polyethylene (HDPE) as an alternate piping material for the replacement of buried steel piping, the issues and lessons learned related to BWR steam dryers subjected to flow induced vibration loading associated with extended power uprate (EPU) conditions, the current conclusions related to quasi-laminar indications in reactor pressure vessel ring forgings, steam generator tube leaks and fluid elastic instability, and lessons learned from Operating plants experience for consideration in new nuclear power plant (NPP) construction.

Steam systems and steam condensate systems provide tragic examples of vapor collapse during fluid transients. Chapter 5 provided examples of vapor collapse during liquid/vapor fluid transients, where small quantities of vapor were present. When larger quantities of vapor are present in steam systems, the fluid mechanics of two-phase flow are far more complex. This chapter provides historical examples of water hammer, a discussion of two-phase transients (vapor collapse), a brief discussion of single-phase transients (blowdown), and some actions to prevent damages during steam system operation.

The Combined Cycle Task Group of the ASME Research and Technology Committee on Water and Steam in Thermal Systems has prepared the following set of chemical operating limits specifically to address the requirements for heat recovery steam generators. A common configuration for power generation utilizes a natural gas-fired combustion turbine (CT) coupled with a heat recovery steam generator (HRSG) that extracts heat from the gas turbine exhaust to produce steam for a separate steam turbine/generator set. Often multiple CT/HRSG units feed a single steam turbine. Some combustion turbines can use fuel oil as either the primary or back up fuel. If steam or hot water is exported to an industrial user, the plant is typically known as a cogeneration facility. Combined cycle (CT plus HRSG) systems are extremely efficient, with the newest configurations approaching twice the heat rate of conventional fossil fuel-fired power plants. Since the plants are typically powered by natural gas, the need for sulfur emission control technologies is almost always eliminated. For these reasons, the combined cycle power plant has become an extremely common configuration for new generating capacity. Though such arrangements were first conceived and built in the mid-1950s, it was not until the mid-1970s that advances in high-temperature materials and air cooling of gas turbine blades made the combined cycle power plant commercially viable.

The primary objective of any water treatment program is the long-term reliability and health of all materials in the steam/water cycle. This requires that water and steam purity be constantly monitored and controlled to prevent corrosion and deposition. Corrosion and deposition are often related; corrosion in one area of the steam/water cycle often results in deposition further downstream in the process. An accumulation of deposits can, conversely, promote corrosion of the underlying metal. Chemical control limits are of little value without frequent and accurate monitoring to ensure compliance. The use of continuous on-line monitoring of pH, specific conductivity, cation (acid) conductivity, sodium, and dissolved oxygen is highly recommended as opposed to grab sample testing once a shift or daily. Such manual testing is insufficient if the plant is to be protected from damage caused by chemistry excursions. On-line monitors must be specified prior to construction, installed during construction, and put into service and calibrated during commissioning. Once the reliability of an on-line analyzer has been verified, grab sampling and accurate analysis is required occasionally to confirm the on-line readings. It is important to realize that the results of grab sample analyses may be more prone to errors than those of on-line monitors.

Lay-up and start-up of a combined cycle power plant are particularly important as the plants are often cycled regularly to meet peak demands. Start-up is not gradual, as in a conventional fossil-fired boiler, but very sudden because the combustion turbine exhaust gases produce very rapid heating of the tubes. Combustion turbine purge cycles that occur just prior to ignition exacerbate the situation by pushing cold air through the HRSG followed by the engine ignition and sudden temperature rise. These factors can produce condensate in superheaters that can result in thermal low-cycle fatigue. This result can be minimized with proper design and operational procedures. Start-up practice should ensure that oxygen is less than or equal to 10 ppb in the feedwater and any other water that will be fed to the HRSG before the deaerator is operational. This stipulation applies to water in the HRSG drums and the condenser hotwell and may even extend to the condensate storage tanks in some configurations. The purity of steam supplied by auxiliary boilers to a HRSG should be the same as that of steam produced by the HRSG.

All-volatile treatment program (AVT) — A treatment program in which all of the treatment components are fully volatile. Cascading blowdown - Cascading blowdown generally refers to the process in which the highest-pressure drum continuous blowdown is directed to a lower-pressure steam drum to improve cycle efficiency. Cation conductivity — The conductivity of a sample after passing it through an acid- form strong acid cation resin column, whereby all cations have been replaced by hydrogen ions.

In 1999, an international collaborative initiative for the development of advanced (Generation IV) reactors was started. The idea behind this effort was to bring nuclear energy closer to the needs of sustainability, to increase proliferation resistance, and to support concepts able to produce energy (both electricity and process heat) at competitive costs. Six reactor concepts were chosen for further development: the sodium fast reactor (SFR), the very-high-temperature gas-cooled reactor (VHTR), the lead or lead-bismuth cooled liquid metal reactor, the helium gas-cooled fast reactor, the molten salt reactor (MSR), and the super critical water reactor. In view of sustainability, the Generation IV reactors should not only have superior fuel cycles to minimize nuclear waste, but they should also be able to produce process heat or steam for hydrogen production, synthetic fuels, refinery processes, and other commercial uses. These reactor types were described in the 2002 Generation IV roadmap. Different projects around the world have been started since that time. The most advanced efforts are with reactors where production experience already existed. These reactors include the SFR and the VHTR. The other reactor types are still more in a design concept phase. This chapter briefly describes the six Generation IV concepts and then provides additional details, focusing on the two near-term viable Generation IV concepts. The current status of the applicable international projects is then summarized. These new technologies have also created remarkable demands on materials compared with light water reactors (LWRs). Higher temperatures, higher neutron doses, environments very different from water, and design lives of 60 years present a real engineering challenge. These new demands have led to many exciting research activities and to new Codes and Standards developments, which are summarized in the final sections of this chapter.

Thermal Power Plants are power plants operating on carbon-based fuel such as coal, natural gas, and petroleum products. There are five major types of thermal power plants in use on the power grid today: Steam Turbine Power Plants produce electric power by creating steam at high pressure and temperature (superheated steam at 2000 psia/138 bars and 1500°F/815°C) in boilers, which is then expanded through a steam turbine causing the turbine to drive a generator, which then produces electric power. The steam leaving the turbine is usually sent to a condenser, which maintains a vacuum and where the steam is condensed back to a liquid condensate (water). The steam turbine follows the Rankine Cycle. Steam turbine power plants can produce up to 2000 MW of power and are most widely used plant types in the world. These plants have a thermal efficiency between 28% and 35%. Simple Cycle Gas Turbine Power Plants are plants that follow the Brayton Cycle; in gas turbines, the air is compressed in the compressor section of the turbine to a high pressure (580 psia/40 bars) and temperature (1300°F/704°C), and in the combustor the air is further heated to a higher temperature (2600°F/1426°C) at constant pressure. The gas leaving the combustor is at a high pressure and high temperature and is then expanded through the turbine section. The gases leaving the turbine are at a pressure of about (15.0 psia/1.03 bars) and a temperature of about (1200°F/649°C). The turbine drives the gas turbine's compressor and the generator, which produces electric power. These gas turbines can produce up to 300 MW of power. The gas turbine power plant can be installed in 12–18 months, and thus have been used widely in developing nations where energy requirements change rapidly. These plants have a thermal efficiency between 25% and 45% depending on the size of the plant.

The subject of this chapter is the capital equipment in a steam power plant that is used to condense the exhaust steam from the lowest pressure turbine, by using water as the cooling medium. In the applied heat transfer literature, such heat transfer equipment is often simply referred to as the “Surface Condenser.” A surface condenser is necessarily a large piece of equipment because more than 60% of the thermal energy produced by a power plant ends up as low enthalpy (waste) heat. This is because of the inherent thermodynamic limitation of the Rankine Cycle, which must be rejected by the condenser to the environment. The heat transfer area in a power plant's surface condenser easily dwarfs that in any other heat exchanger in the plant. Classical thermodynamics holds that the lower the temperature of the heat sink, the higher the efficiency of the Carnot cycle. Therefore, attaining the lowest possible condensing temperature in the heat sink of the Rankine Cycle—the surface condenser—is a primary goal in surface condenser design. Since the saturation temperature and pressure of steam vary in a proportional manner at low pressures, the objective of low condensing temperature translates to that of a low condenser operating pressure. Accordingly, surface condensers are operated at as high a level of vacuum (typically 1.0 to 2.5 in. of mercury absolute) as the quantity and temperature of the cooling water would allow. The subatmospheric condition in the condenser and portions of turbine assembly and auxiliaries promotes leakage of air into the system. In boiling water type of nuclear plants the motive steam acquires additional non-condensibles due to radiological disassociation of water into hydrogen and oxygen. Whatever their origin, these so-called non-condensibles tend to collect in the lowest pressure region in the power cycle which is the steam space in the surface condenser. Unless removed continuously and efficiently, they may sharply interfere with the heat transfer process in the condenser. Kern [8] quotes observed data of Othmer which indicates that even 1% volumetric concentration of air in steam reduces the condensing film coefficient by approximately 45%. The oxygen in the non-condensibles is another source of concern. Oxygen is known to actuate corrosion of condenser internals. Austenitic stainless steel tubing can become highly susceptible to stress corrosion in the presence of even small concentrations of oxygen. Therefore, efficient collection and removal of non-condensibles is of paramount importance in surface condenser design. A reliable design for collection and expulsion of the non-condensibles is particularly important in the surface condensers used in geothermal plants where the steam extracted from the ground has a large fraction of associated gases.

Section I applies to several types of boilers and components of boilers, such as economizers, superheaters, reheaters, and, in some circumstances, feedwater heaters. Although its title is Rules for Construction of Power Boilers, its scope is somewhat broader. The Preamble to Section I explains that it covers electric boilers, miniature boilers, high-temperature water boilers, heat recovery steam generators, certain fired pressure vessels, and organic fluid vaporizers. Since the precise definitions of these various types of boilers are not generally known, the following definitions, found in footnotes to the Preamble, are helpful: Power boiler —a boiler in which steam or other vapor is generated at a pressure of more than 15 psi (100 kPa) for use external to itself. Electric boiler —a power boiler or a high-temperature water boiler in which the source of heat is electricity. Miniature boiler —a power boiler or high-temperature water boiler in which the limits in PMB-2 are not exceeded. (PMB-2 establishes limits on shell diameter, heating surface, gross volume, and maximum allowable working pressure. See further discussion under Part PMB later in this chapter.) High-temperature water boiler —a water boiler intended for operation at either pressures in excess of 160 psi (1.1 MPa) or temperatures in excess of 250° F (120°C), or both. Heat recovery steam generator (HRSG) —a boiler that has as its principal source of thermal energy a hot gas stream having high-ramp rates and temperatures such as the exhaust of a gas turbine. Fired pressure vessel —reheater, isolable superheaters, and nonintegral separately fired superheaters.